1. Field of the Invention
The present invention relates, generally, to methods for preparing uranium metal and apparatus thereused, more particularly, to methods for preparing uranium metal capable of separating pure uranium metal with high capability from the spent metallic nuclear fuels generated in an atomic power plant conveniently and economically and an apparatus thereused.
In a uranium metal electrorefining, if the sections of the used metal fuels are put in an anode basket within a molten salt at 500° C. where uranium trichloride is melted and a current is applied using a metal rod such as iron as cathode, the uranium trichloride in the molten salt is deposited. In this reaction, the separated chloride ions electrically dissolve uranium metal in the anode and can separate pure uranium metal at the cathode. However, this method is disadvantageous in that the reaction occurs at a low speed thus a great amount of products are not obtained within a short time.
2. Description of the Related Art
In the method for separating a uranium metal with a high capability, as shown in U.S. Pat. Nos. 5,650,053 and 6,365,019 and application No. 2004/01347851A1, the sections of the spent metal fuels in the molten salt at 500° C. are put in an anode basket of a perforated plate and placed in and out the cathode formed in a tube type, consisting of several anode baskets, and then if an electricity is applied with rotating the anode basket, the uranium metal in the anode is dissolved out to be deposited in the cathode and the deposited uranium is scraped downwardly by a ceramic plate attached the outside of the anode and collected in the lower collecting apparatus. However, as the apparatus partially detach the electrodeposited uranium metal, the remaining electrodeposits continue to stick on the cathode surface. Accordingly, the sticking electrodeposits become a compact tissue which is difficult to be detached and the anode ceramic plate cannot detach this compact electrodeposites. Therefore, if the electrorefining is stopped after a certain time passes, and an electricity is inversely applied, the compactly sticking uranium eletrodeposites are return back to anode and stripped. After the cathode surface is cleaned, the operation for electrodepositing is needed again. This operation is disadvantageous in that a great amount of electricity is consumed and the electrodeposition capability is very ineffective, thus the apparatus is very complicated.
In order to solve the above disadvantage, the US Argonne National Laboratory developed a new apparatus called Plannar electrode Electrorefiner (PEER) at http://www.cmt.anl.gov. The apparatus is designed to deposit an anode including a metallic fuel in the middle and a plurality of cathodes therearound and operate an electrolytic reaction. After a certain time passes, the eletrodeposites are attached on the cathode and a porous ceramic plate is moved in a vertical direction to scrap out the cathode electrodeposites. However, this method is disadvantageous in that the electrodeposites are intervened between the hole of the ceramic plate and a metal cathode to prevent the vertical movements, and the complicated apparatus is not greatly improved. Especially, the method is also disadvantageous in that a process for removing the electrodeposites sticked on the cathode via the stripping process using the second cathode is included to degrade the efficiency of a current greatly.